In one technology, a rolling bearing having a sensor that measures the state of rotation (indicative of, for example, rotational speed, number of rotations, or rotating direction, hereinafter, also referred to as “rotating state”) of the rotating ring is known. In a rolling bearing having such a sensor, as the sensor is attached at one end side in the axial direction of the rolling bearing, the other end side in the axial direction can be sealed by attaching seal, but one end side in the axial direction at which the sensor is attached has to be devised for sealing.
For example, Patent Literatures 1 and 2 each disclose a rolling bearing having a sensor, in which a mechanism of preventing the entering of foreign materials is arranged at one end side in the axial direction at which the sensor is attached to suppress the entering of the foreign materials into the sensor or the rolling bearing. This rolling bearing having the sensor includes an inner ring that is a rotating side bearing ring, an outer ring that is a fixed side bearing ring (non-rotating ring), rolling elements rotatably arranged between both rings, and a sensor that measures the rotating state of the bearing.
The sensor includes a detected object that rotates in an identical rotating state to the inner ring, a detecting body that detects the rotating state of the detected object, and a sensor housing that accommodates the detecting body. The detected object is fixed at the inner ring and rotates integrally with the inner ring, whereas the detecting body is fixed at the outer ring with being accommodated in the sensor housing to be capable of facing the detected object at a predefined space from the detected object. Then, the sensor housing includes the mechanism of preventing the entering of foreign materials from a gap between the inner ring and the sensor housing.
The rolling bearing having the sensor disclosed by Patent Literature 1 includes a foreign material entering prevention portion with a following configuration, as the mechanism of preventing the entering of foreign materials from the gap between the inner ring and the sensor housing. That is, the detected object is rotating together with the inner ring with being attached to a detected object holder fixed at the inner ring. The foreign material entering prevention portion is formed to protrude toward the detected object holder on a whole circumference of a facing surface, of the sensor housing, facing the detected object holder. Then, the sensor housing is located such that a protrusion end of the foreign material entering prevention portion faces the detected object holder at a predefined space therefrom, and a facing space between the protrusion end of the foreign material entering prevention portion and the detected object holder is set to be smaller than the facing space between the detected object and the detecting body.
In addition, the rolling bearing having the sensor disclosed by Patent Literature 2 includes a foreign material entering prevention portion with a following configuration, as the mechanism of preventing entering of foreign materials from the gap between the inner ring and the sensor housing. That is, the detected object is rotating together with the inner ring with being attached to a detected object holder fixed at the inner ring. The foreign material entering prevention portion is partially formed of an elastic material, one end side in the axial direction is fixed to the sensor housing, and a seal lip formed at the other end side is in sliding contact with the detected object holder or the inner ring side face.